Designation F1536 − 95 (Reapproved 2015)´1 Standard Test Method for Determining Strength and Setting Time of Synthetic Water Activated Polyurethane Fiberglass Orthopaedic Casting Tape1 This standard i[.]
Trang 1Designation: F1536−95 (Reapproved 2015)
Standard Test Method for
Determining Strength and Setting Time of Synthetic
Water-Activated Polyurethane Fiberglass Orthopaedic Casting
Tape1
This standard is issued under the fixed designation F1536; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision A number in parentheses indicates the year of last reapproval A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε 1 NOTE—Editorial corrections were made in June 2016.
1 Scope
1.1 This test method covers the functional diametral
com-pression strength of cylindrical test specimens formed from
synthetic fiberglass polyurethane casting materials The test
specimens employed in this test method are similar in
geom-etry and construction to casts used in orthopaedic applications
This test method is not intended to determine the strength of
the base materials used for fabrication of the test specimen
1.2 The values stated in inch-pound units are to be regarded
as standard The values given in parentheses are mathematical
conversions to SI units that are provided for information only
and are not considered standard
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use It is the
responsibility of the user of this standard to establish
appro-priate safety and health practices and determine the
applica-bility of regulatory limitations prior to use Specific warning
statements are given in 6.7
2 Referenced Documents
2.1 ASTM Standards:2
E4Practices for Force Verification of Testing Machines
E691Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
3 Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 diametral compression strength—the load per unit
width in lbs/in (Newtons/mm), calculated by dividing either
the peak failure load or the maximum deflection load by the nominal sample length (that is, manufacturer’s stated tape width)
3.1.2 maximum deflection load—the test cylinder is
com-pressed 0.4 in (10 mm) from the initial load position without noticeable failure or a measurable decrease in load The load at 0.4 in (10 mm) deflection shall be called the maximum deflection load
3.1.3 peak failure load—failure of the test cylinder with a
concomitant decrease in load prior to 0.4 in (10 mm) diametral compression The highest load attained prior to the decrease shall be called the peak failure load
4 Summary of Test Method
4.1 A test cylinder is prepared by immersing the casting tape
in 75 6 2°F (23.9 6 1.1°C) water, squeezing per the manufacturer’s instructions under the surface of the water, and then wrapping around either a 2.0 in (50.8 mm) or 2.5 in (63.5 mm) outside diameter cylindrical mandrel The tape is wrapped layer upon layer producing a five layer cylinder The test cylinder is removed from the mandrel after an initial setting period After a specified time, the test specimen is positioned
on its side between two flat platens in the testing machine and compressed to determine its strength Ambient temperature and humidity are specified because of their pronounced effect on material properties during the curing period
5 Significance and Use
5.1 Diametral compression strength is an important measure
of the mechanical properties of casting materials This test method simulates the loading pattern seen in lower extremity casting applications during ambulation This test method can-not be used to determine cast life or measure bending or other modes of cast failure
5.2 This test method measures but does not prescribe values
6 Apparatus
6.1 Testing Machines—Machines used for compression
test-ing shall conform to the requirements of Practices E4 For
1 This test method is under the jurisdiction of ASTM Committee F04 on Medical
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
F04.15 on Material Test Methods.
Current edition approved May 1, 2015 Published July 2015 Originally approved
in 1995 Last previous edition approved in 2010 as F1536 – 95 (2010) DOI:
10.1520/F1536-95R15E01.
2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Trang 2universal machines with a common test space, calibration shall
be performed in compression
6.1.1 The surfaces of the flat platens shall be perpendicular
to the loading axis and parallel at all times within 0.005 in./in
(1.3 mm/mm) Platen surfaces should be clean and free of
corrosion
6.1.2 The testing machine shall be capable of producing a
constant compression rate between 1 to 10 in./min (25.4 to 254
mm/min)
6.1.3 The testing machine shall be capable of measuring the
compressive load within 60.5 lbs (2.2 N)
6.2 Test Specimen Preparation Mandrel—A solid,
cylindri-cal aluminum mandrel of sufficient length to accommodate
three test specimens without end contact shall be mounted in a
horizontal position (see Fig 1) Either of two mandrel
diam-eters may be used: Type I—2.00 in (50.8 mm) diameter, or
Type II—2.50 in (63.5 mm) diameter
6.2.1 Option—Three individual mandrels, either Type I or
Type II, each capable of holding one test specimen, may be
substituted for a single, solid mandrel
6.3 Constant Tension Method—Each layer of tape shall be
wrapped on the mandrel at a constant tension of 0.25 lbs/in
(4.5 g/mm) width of tape Suggested methods for
accomplish-ing this include the use of a dead weight clamped to the free end of the tape while the horizontally mounted mandrel is manually rotated (see Fig 1), or the use of an automated constant torque winding mechanism (see Fig 2)
6.4 Water Container—A container capable of holding at
least 1 gal (3.78 L) of water and of sufficient depth to allow complete immersion of the casting tape
6.5 Release Liner—A sheet form liner of nominal thickness,
such as waxed paper, shall be used to cover the mandrel and prevent adhesion of the resin to the mandrel The liner shall allow release of the cured specimen from the mandrel with minimal force, and shall be easily removable from the speci-men inner diameter prior to compression testing
6.6 Timer—A timing device accurate to 61 s.
6.7 Gloves—Gloves capable of protecting the hands from
contact with the resin, for example, latex surgical gloves
(Warning—Contact with uncured or curing resins should be
avoided These resins may adhere to the skin and be difficult to remove In addition, most polyurethane resins contain isocya-nate to which some individuals are or may become sensitized Gloves should be worn at all times when handling uncured or curing casting tape.)
FIG 1 Manual Preparation Method
Trang 36.8 Thermometer— A device capable of measuring
tempera-tures within 61°F (0.5°C) in the 70 to 80°F (21.1 to 26.7°C)
range
7 Reagents and Materials
7.1 At least three rolls of the casting tape shall be tested; one
roll for each of the three specified time periods Three test
cylinders shall be prepared from each roll without the use of
manual molding techniques
N OTE 1—If testing of cylinders with the use of manual molding is
desired, a secondary group of samples should be prepared using the
desired molding technique.
7.2 Water for initiation of the curing process shall be
maintained at 75 6 2°F (23.9 6 1.1°C)
7.2.1 The water shall be changed after three rolls have been
prepared
8 Sample Conditioning
8.1 Store each package flat, with each roll on its side, at 70
6 5°F (21.1 6 2.8°C) for at least 24 h before use
8.2 Open each package immediately prior to use
9 Specimen Preparation
9.1 Before opening each package, record the manufacturer’s
name, product description, size (width and length), and lot
number
9.2 Wrap the release liner around the test specimen
prepa-ration mandrel and secure with tape
9.3 Open the package and loosely grasp roll with core
perpendicular to fingers in palm of hand
9.4 Start the timer, fully immerse roll in water and squeeze
following manufacturer’s instructions Record immersion time
and number of squeezes
9.5 Remove the roll from the water and allow excess water
to drain for not more than five seconds DO NOT SQUEEZE
to remove excess water
9.6 Wrap a five-ply cylinder on the mandrel as rapidly as possible using constant tension (see Fig 1 or Fig 2) Each succeeding layer shall be aligned directly over the preceding layer with complete overlap Cut the tape at the end of the fifth ply within 61⁄4in (6.4 mm) relative to the starting end of the first ply
9.7 Immediately wrap a second five-ply cylinder as rapidly
as possible by repeating 9.6 9.8 Immediately wrap a third five-ply cylinder as rapidly as possible by repeating9.6 Cut off excess tape
9.9 Molding—Primary test samples should be prepared
without the use of manual molding If testing of samples with the use of manual molding is desired, a secondary group of samples should be prepared using the desired molding tech-nique Record the molding time and degree of manipulation used
9.10 Setting Time—This is determined by a manual
inden-tation test, that is, the time elapsed from the initial immersion until the test cylinder cannot be indented by moderate finger-nail pressure Begin indentation testing for material setting after all three samples from a single roll are wrapped Repeat the test every 15 s until all samples are set Record the three
times and report the average as the setting time.
9.11 After the test cylinders have set, remove them from the mandrel taking care to avoid deforming them Remove the release liner from the inside of the test cylinders
9.12 Stand test specimens on end with enough space be-tween samples to allow air to freely circulate bebe-tween the cylinders
10 Procedure
10.1 Testing Speed—The recommended constant crosshead
(or actuator) speed shall be between 1 to 10 in./min (25.4 to
254 mm/min) Report the exact speed
N OTE 2—Testing speeds outside the recommended range may be used provided that there are no demonstrable rate-dependent effects on the
FIG 2 Automated Constant Torque Preparation Method
Trang 4material and that complete data capture is assured at higher rates.
10.2 Load Range Selection—Set the load range of the
testing machine so that the maximum expected load is at least
20 % of the range selected
10.3 Thirty Minute Diametral Compression Strength—This
test is performed 30 6 5 min after the time of initial immersion
of the sample roll
10.3.1 Place each specimen, one at a time, between the
platens of the testing machine Center the test cylinder on the
lower platen, the platen being sufficiently large to support the
specimen over its entire length Orient the test cylinder so that
the transition or overlap area, that is, where the first ply begins
and the fifth ply ends, is in contact with either the upper or
lower platen
N OTE 3—The presence or absence of an overlap between the first and
fifth ply affects the strength of the transition area, by either increasing or
decreasing it from that of the surrounding area with a uniform number of
plies Since sample failure generally occurs in regions of high tensile
stress on the free outer wall of the test cylinder, it is important that the
overlap, or transition area, not be in the high tensile stress region.
10.3.2 Bring the platens together until they just touch the
test cylinder, but no load has been applied
10.3.3 Initiate the test at the prescribed rate Continue the
test at a uniform rate until the one of the following conditions
occurs: either cylinder failure occurs or the maximum
deflec-tion is reached
10.3.4 If the test cylinder has not set in 30 min, do not test
for the 30 min diametral compression strength
10.3.5 Record for each cylinder the maximum reading in
pounds (Newtons), that is, the peak failure load or the
maximum deflection load, whichever occurs first The 30 min
diametral compression strength is the average of the three
values calculated from the readings
10.4 Sixty Minute Diametral Compression Strength—This
test is identical to the 30 min diametral compression test and is
performed 60 6 5 min after the time of initial immersion of the
sample roll
10.5 Twenty-Four Hour Diametral Compression Strength—
This test is identical to the 30 and 60 min diametral compres-sion tests and is performed 24 h 6 30 min after the time of initial immersion of the sample roll
10.5.1 Maintain specimens for the 24 h diametral compres-sion test at 75 6 5°F (23.9 6 2.8°C) and 50 6 10 % relative humidity for the 24 h curing period
11 Report
11.1 Report the following information:
11.1.1 Product Identity—Manufacturer, product description,
product size (width and length) and manufacturing lot code;
11.1.2 Initiation Data—Total immersion time and number
of squeezes used for initiation of polymerization;
11.1.3 Set Time—Average of the three measurements (in
seconds);
11.1.4 Constant Tension Method—Manual or automated; 11.1.5 Mandrel Type—Type I or Type II;
11.1.6 Testing Speed—Report crosshead or (actuator)
dis-placement rate as inch/min (mm/min);
11.1.7 Diametral Compression Strengths—Average of the
three (3) calculated values for each roll tested at each time
interval Report the load type (peak failure or maximum
deflection); and
11.1.8 Molding—Degree and duration of molding used on a
secondary set of samples
12 Precision and Bias
12.1 Precision and bias of this test method will be deter-mined after interlaboratory tests are carried out and the results tabulated The interlaboratory tests will be carried out follow-ing Practices E691
13 Keywords
13.1 orthopaedic casting tape—diametral compression strength; orthopaedic casting tape—mechanical testing; ortho-paedic casting tape—setting time; polyurethane—biomedical applications; polyurethane/fiberglass orthopaedic casting tape
APPENDIX
(Nonmandatory Information) X1 RATIONALE
X1.1 The primary purpose of this test method is to provide
a standard method for determining the strength and setting time
of synthetic water-activated polyurethane fiberglass
orthopae-dic casting tape This includes sample preparation, testing
procedure, and data reporting
X1.2 Specimen preparation in this test method is not
in-tended to duplicate all actual casting tape use It is inin-tended to
produce uniform samples upon which mechanical testing may
be performed with minimal variability
X1.3 Wrapping by hand may produce samples in which
there are variations in adhesion between layers, or along the
sample width because of variations in wrapping tension Sample-to-sample variation may also be increased when using manual methods Therefore, samples should be prepared using
a method that employs constant tension during wrapping of the plies (see Fig 1andFig 2)
X1.4 Manual molding of the casting tape, while an integral part of the normal cast application process, is extremely subjective, making standardization of this process difficult Variations in molding pressure and molding time can greatly influence test results Therefore, this test method provides for testing to be performed on a primary set of specimens prepared
Trang 5without molding Should it be desirable to quantify the effects
of molding, a secondary set of samples should be prepared with
a molding technique
X1.5 The mandrel diameters (Type I and Type II) were
selected based on the need to limit the number of possible
diameters and still remain in a reasonable anatomic size range
Mandrel material has been limited to aluminum in order to
maintain reasonable fixture mass, and to provide a material that
was relatively corrosion-resistant Because ferrous metals,
non-ferrous metals, and polymers have intrinsically different
masses and heat conduction coefficients, changes in materials
or design (that is, solid versus hollow) could alter heat
conduction between the mandrel and the curing tape If the
peak exothermic temperature or the curing temperature profile
was affected in this manner, unpredictable changes in setting
time and measured compression strengths could result X1.6 The testing procedure in this test method is not intended to replicate actual casting tape use, nor duplicate all failure modes It is meant to provide a standard, repeatable test method for comparison of the relative strengths for various synthetic water-activated polyurethane fiberglass orthopaedic casting tapes The prescription of tests at 30 min, 60 min and
24 h is intended to provide useful information regarding the curing profile for materials tested, and provide some objective measure of relative strengths for partially cured and fully cured casting tape samples
X1.7 This test method is not intended to restrict the curing temperature regimes should alternate curing chemistries be developed
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